Method of ligating hollow anatomical structures

ABSTRACT

A catheter includes a plurality of expandable primary leads to deliver energy to a fallopian tube, a vein such as a hemorrhoid or an esophageal varix, or another hollow anatomical structure requiring ligation or occlusion. Each of the primary leads includes an electrode located at the working end of the catheter. Separation is maintained between the primary leads such that the leads can receive power of selected polarity. The primary leads are constructed to expand outwardly to place the electrodes into apposition with a hollow anatomical structure. High frequency energy can be applied from the leads to create a heating effect in the surrounding tissue of the anatomical structure. The diameter of the hollow anatomical structure is reduced by the heating effect, and the electrodes of the primary leads are moved closer to one another.

This application is a continuation-in-part of application Ser. No.08/927,251 filed on Sep. 11, 1997 and application Ser. No. 08/958,766filed on Oct. 26, 1997.

BACKGROUND OF THE INVENTION

The invention relates generally to a method for applying energy toshrink a hollow anatomical structure, such as a fallopian tube or avein, including, but not limited to, superficial and perforator veins,hemorrhoids, and esophageal varices, and more particularly, to a methodusing an electrode device having multiple leads for applying radiofrequency (RF) energy, microwave energy, or thermal energy.

The human venous system of the lower limbs consists essentially of thesuperficial venous system and the deep venous system with perforatingveins connecting the two systems. The superficial system includes thelong or great saphenous vein and the short saphenous vein. The deepvenous system includes the anterior and posterior tibial veins whichunite to form the popliteal vein, which in turn becomes the femoral veinwhen joined by the short saphenous vein.

The venous system contains numerous one-way valves for directing bloodflow back to the heart. Venous valves are usually bicuspid valves, witheach cusp forming a sack or reservoir for blood which, under retrogradeblood pressure, forces the free surfaces of the cusps together toprevent retrograde flow of the blood and allows only antegrade bloodflow to the heart. When an incompetent valve is in the flow path, thevalve is unable to close because the cusps do not form a proper seal andretrograde flow of the blood cannot be stopped. When a venous valvefails, increased strain and pressure occur within the lower venoussections and overlying tissues, sometimes leading to additional valvularfailure. Two venous conditions which often result from valve failure arevaricose veins and more symptomatic chronic venous insufficiency.

The varicose vein condition includes dilation and tortuosity of thesuperficial veins of the lower limbs, resulting in unsightlydiscoloration, pain, swelling, and possibly ulceration. Varicose veinsoften involve incompetence of one or more venous valves, which allowreflux of blood within the superficial system. This can also worsen deepvenous reflux and perforator reflux. Current treatments of veininsufficiency include surgical procedures such as vein stripping,ligation, and occasionally, vein-segment transplant.

Chronic venous insufficiency involves an aggravated condition ofvaricose veins which may be caused by degenerative weakness in the veinvalve segment, or by hydrodynamic forces acting on the tissues of thebody, such as the legs, ankles, and feet. As the valves in the veinsfail, the hydrostatic pressure increases on the next venous valves down,causing those veins to dilate. As this continues, more venous valveswill eventually fail. As they fail, the effective height of the columnof blood above the feet and ankles grows, and the weight and hydrostaticpressure exerted on the tissues of the ankle and foot increases. Whenthe weight of that column reaches a critical point as a result of thevalve failures, ulcerations of the ankle begin to form, which start deepand eventually come to the surface. These ulcerations do not heal easilybecause of poor venous circulation due to valvular incompetence in thedeep venous system and other vein systems.

Other related venous conditions include dilated hemorrhoids andesophageal twisted veins. Pressure and dilation of the hemorrhoid venousplexus may cause internal hemorrhoids to dilate and/or prolapse and beforced through the anal opening. If a hemorrhoid remains prolapsed,considerable discomfort, including itching and bleeding, may result. Thevenous return from these prolapsed hemorrhoids becomes obstructed by theanal sphincters, which gives rise to a strangulated hemorrhoid.Thromboses result where the blood within the prolapsed vein becomesclotted. This extremely painful condition can cause edema andinflammation.

Varicose veins called esophageal varices can form in the venous systemwith submucosa of the lower esophagus, and bleeding can occur from thedilated veins. Bleeding or hemorrhaging may result from esophagealvarices, which can be difficult to stop and, if untreated, could developinto a life threatening condition. Such varices erode easily, and leadto a massive gastrointestinal hemorrhage.

Ligation of a fallopian tube (tubal ligation) for sterilization or otherpurposes is typically performed by laparoscopy. A doctor severs thefallopian tube or tubes and ties the ends. External cauterization orclamps may also be used. General or regional anesthetic must be used.All of the above are performed from outside the fallopian tube.

Hemorrhoids and esophageal varices may be alleviated by intra-luminalligation. As used herein, “ligation” or “intra-luminal ligation”comprises the occlusion, collapse, or closure of a lumen or hollowanatomical structure by the application of electrical energy from withinthe lumen or structure. As used herein, “ligation” or “intra-luminalligation” includes electro-ligation. In the case of fallopian tubeligation, it would be desirable to perform the ligation from within thefallopian tube itself (intra-fallopian tube) to avoid the traumaassociated with external methods.

Ligation involves the cauterization or coagulation of a lumen usingenergy, such as that applied through an electrode device. An electrodedevice is introduced into the lumen and positioned so that it contactsthe lumen wall. Once properly positioned, RF energy is applied to thewall by the electrode device thereby causing the lumen to shrink incross-sectional diameter. In the case of a vein, a reduction incross-sectional diameter of the vein, for example from 5 mm (0.2 in) to1 mm (0.04 in), significantly reduces the flow of blood through a lumenand results in an effective occlusion. Although not required foreffective occlusion or ligation, the vein wall may completely collapsethereby resulting in a full-lumen obstruction that blocks the flow ofblood through the vein. Likewise, a fallopian tube may collapsesufficient to effect a sterilization of the patient.

One apparatus for performing ligation includes a tubular shaft having anelectrode device attached at the distal tip. Running through the shaft,from the distal end to the proximal end, are electrical leads. At theproximal end of the shaft, the leads terminate at an electricalconnector, while at the distal end of the shaft the leads are connectedto the electrode device. The electrical connector provides the interfacebetween the leads and a power source, typically an RF generator. The RFgenerator operates under the guidance of a control device, usually amicroprocessor.

The ligation apparatus may be operated in either a monopolar or bipolarconfiguration. In the monopolar configuration, the electrode deviceconsists of an electrode that is either positively or negativelycharged. A return path for the current passing through the electrode isprovided externally from the body, as for example by placing the patientin physical contact with a large low-impedance pad. The current flowsfrom the ligation device through the patient to the low impedance pad.In a bipolar configuration, the electrode device consists of a pair ofoppositely charged electrodes of approximately equal size, separatedfrom each other, such as by a dielectric material or by a spatialrelationship. Accordingly, in the bipolar mode, the return path forcurrent is provided by an electrode or electrodes of the electrodedevice itself. The current flows from one electrode, through the tissue,and returns by way of the oppositely charged electrode.

To protect against tissue damage; i.e., charring, due to cauterizationcaused by overheating, a temperature sensing device is attached to theelectrode device. The temperature sensing device may be a thermocouplethat monitors the temperature of the venous tissue. The thermocoupleinterfaces with the RF generator and the controller through the shaftand provides electrical signals to the controller which monitors thetemperature and adjusts the energy applied to the tissue through theelectrode device accordingly.

The overall effectiveness of an ligation apparatus is largely dependenton the electrode device contained within the apparatus. Monopolar andbipolar electrode devices that comprise solid devices having a fixedshape and size can limit the effectiveness of the ligating apparatus forseveral reasons. Firstly, a fixed-size electrode device typicallycontacts the vein wall at only one point on the circumference or innerdiameter of the vein wall. As a result, the application of RF energy ishighly concentrated within the contacting venous tissue, while the flowof RF current through the remainder of the venous tissue isdisproportionately weak. Accordingly, the regions of the vein wall nearthe point of contact collapse at a faster rate then other regions of thevein wall, resulting in non-uniform shrinkage of the vein lumen whichcan result in inadequacy of the overall strength of the occlusion andthe lumen may eventually reopen. To avoid an inadequate occlusion, RFenergy must be applied for an extended period of time so that thecurrent flows through the tissue generating thermal energy includingthrough the tissue not in contact with the electrode to cause thattissue to shrink sufficiently also. Extended applications of energy havea greater possibility of increasing the temperature of the blood to anunacceptable level and may result in a significant amount ofheat-induced coagulum forming on the electrode and in the vein which isnot desirable. This can be prevented by exsanguination of the vein priorto the treatment, and through the use of temperature regulated powerdelivery.

Secondly, the effectiveness of a ligating apparatus having a fixed-sizeelectrode device is limited to certain sized veins. An attempt to ligatea vein having a diameter that is substantially greater than theelectrode device can result in not only non-uniform heating of the veinwall as just described, but also insufficient shrinkage of the veindiameter. The greater the diameter of the vein relative to the diameterof the electrode device, the weaker the energy applied to the vein wallat points distant from the point of electrode contact. Accordingly thevein wall is likely to not completely collapse prior to the venoustissue becoming over cauterized at the point of electrode contact. Whilecoagulation as such may initially occlude the vein, such occlusion mayonly be temporary in that the coagulated blood may eventually dissolverecanalizing the vein. One solution for this inadequacy is an apparatushaving interchangeable electrode devices with various diameters. Anothersolution would be to have a set of catheters having different sizes sothat one with the correct size for the diameter of the target vein willbe at hand when needed. Such solutions, however, are both economicallyinefficient and can be tedious to use. It would be desirable to have asingle catheter device that is usable with a large range of sizes oflumina.

Although described above in terms of a vein, the concepts are generallyapplicable to other hollow anatomical structures in the body as well.For consideration of avoiding unnecessary repetition, the abovedescription has been generally confined to veins.

Hence those skilled in the art have recognized a need for a methodcapable of more evenly distributing RF energy along a circumferentialband of a wall of the target anatomical structure where the wall isgreater in diameter than the electrode device, and thereby provide morepredictable and effective occlusion of anatomical structures whileminimizing the formation of heat-induced coagulum. Such method should beapplicable to the ligation of all the veins in the body, including butnot limited to perforator and superficial veins, as well as hemorrhoids,esophageal varices, and also fallopian tubes. The invention fulfillsthese needs and others.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides a methodfor applying energy along a generally circumferential band of the wallof a hollow anatomical structure, such as a fallopian tube, ahemorrhoid, or an esophageal varix. The application of energy inaccordance with this method results in a more uniform and predictableshrinkage of the vein wall.

In one aspect, the invention comprises a method of applying energy to ahollow anatomical structure from within the structure. The methodincludes the step of introducing a catheter into the anatomicalstructure; the catheter having a working end and a plurality of leads,each lead having a distal end, and each lead being connected to a powersource. The method also includes the step of expanding the leadsoutwardly through the distal orifice and expanding the leads until eachelectrode contacts the anatomical structure. The method further includesthe step of applying energy to the anatomical structure from the distalend of the leads, until the anatomical structure collapses to aneffective occlusion.

In further aspects, the invention is directed to a method of applyingenergy intraluminally to a fallopian tube from a power source,comprising the steps of introducing into the fallopian tube, hemorrhoid,or esophageal varix a catheter having a working end with a plurality ofprimary leads disposed at the working end, each primary lead having adistal end and being connected to the power source, expanding theprimary leads outwardly from the working end of the catheter, whereinthe distal ends of the primary leads move away from each other and intocontact with the wall of the fallopian tube, hemorrhoid, or esophagealvarix, and applying energy to the fallopian tube, hemorrhoid, oresophageal varix from the distal end of the primary leads to collapsethe fallopian tube, hemorrhoid, or esophageal varix to effectivelyocclude the fallopian tube, hemorrhoid, or esophageal varix. In afurther aspect, the step of expanding the primary leads comprises thestep of expanding the primary leads such that the distal ends of theprimary leads are spaced no more than five millimeters apart along thefallopian tube, hemorrhoid, or esophageal varix.

In more detailed aspects, the method further comprises the step ofextending the primary leads through an orifice formed in the working endof the catheter and expanding the primary leads, wherein the distancebetween two mutually opposed expanded distal ends is greater than thediameter of the working end. In another aspect, the method comprises thestep of moving an outer sleeve away from the primary leads such that theprimary leads extend past an orifice of the outer sleeve at the workingend of the catheter and expand outwardly.

In yet further aspects, the method further comprising the steps ofmaintaining separation between the primary leads at a selected locationwith an alignment device positioned inside an outer sheath of thecatheter, and moving the outer sheath in relation to the alignmentdevice to extend the primary leads out the orifice. Furthermore, themethod further comprises the steps of attaching the primary leads to aninner sheath, maintaining separation between the primary leads at aselected location with an alignment device positioned inside an outersheath of the catheter, and moving the outer sheath in relation to theinner sheath to extend the primary leads through the orifice.

In other more detailed aspect, the step of introducing a catheter havinga plurality of primary leads into the fallopian tube, hemorrhoid, oresophageal varix comprises the step of introducing a plurality ofprimary leads that are mounted to the working end in a cantileverarrangement. The method further comprises the step of moving an outersleeve away from the cantilevered primary leads such that the primaryleads extend past an orifice of the outer sleeve at the working end ofthe catheter and expand outwardly.

In a further aspect, the method further comprises the step of moving thecatheter in the fallopian tube, hemorrhoid, or esophageal varix whilecontinuing to apply energy to the fallopian tube, hemorrhoid, oresophageal varix.

In a further detailed aspect, the method further comprises the step ofmounting a secondary lead to the working end, the secondary lead havinga distal end and having a length exceeding that of the primary leads,wherein the step of extending the plurality of primary leads furtherincludes the step of extending the secondary lead through the distalorifice. In another aspect, the step of applying energy to the fallopiantube, hemorrhoid, or esophageal varix comprises the steps of controllingthe power source so that adjacent primary leads are of opposite polaritywhile maintaining the secondary lead so that it is electrically neutral,switching the polarity of the primary leads so that they are all of thesame polarity upon collapse of the fallopian tube, hemorrhoid, oresophageal varix around the primary leads, and controlling the powersource so that the secondary lead is of opposite polarity relative tothe primary leads upon performing the step of switching the polarity ofthe primary leads so that they are of the same polarity.

In further aspects, a bend is formed in each primary lead, the bendformed in the direction away from the other primary leads such that eachprimary lead tends to move outward away from the other primary leads inthe step of expanding the primary leads away from each other. The stepsof sensing the temperature at the distal end of a primary lead andcontrolling the application of power to the primary leads in response tothe temperature sensed at the distal end may also be included.

In another aspect, the method includes the step of compressing thehollow anatomical structure, such as a vein or fallopian tube, to reducethe anatomical structure to a desired size, and for exsanguination,before and/or during the application of energy to occlude or ligate thestructure.

In yet another aspect, the method includes the step of flushing thehollow anatomical structure with fluid before the step of applyingenergy.

These and other aspects and advantages of the present invention willbecome apparent from the following more detailed description, when takenin conjunction with the accompanying drawings which illustrate, by wayof example, embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an energy application system with a partialcutaway view of a catheter showing both the working end which includes aplurality of outwardly expandable electrodes for applying energy totissue and the connecting end which is connected to a power sourcecontrolled by a microprocessor controller for controlling the energyapplied to the electrodes of the working end;

FIG. 2 is a cross-sectional view of the working end of a firstembodiment of a catheter in accordance with aspects of the inventiondepicting the electrodes in a fully expanded position;

FIG. 2a is an end view of the working end of the first embodiment of thecatheter taken along line 2 a—2 a of FIG. 2;

FIG. 3 is a cross-sectional view of the working end of the firstembodiment depicting the electrodes in a fully retracted position;

FIG. 4 is a cross-sectional view of the working end of a second catheterin accordance with principles of the invention depicting the electrodesin a fully expanded position;

FIG. 4a is an end view of the second embodiment of the invention takenalong line 4 a—4 a of FIG. 4;

FIG. 5 is a cross-sectional view of the working end of the secondembodiment of the catheter of FIG. 4 depicting the electrodes in a fullyretracted position;

FIG. 6 is a cross-sectional view of an anatomical structure containingthe catheter of FIG. 2 with the electrodes in apposition with theanatomical structure;

FIG. 6a is an end view of the anatomical structure containing thecatheter taken along line 6 a—6 a of FIG. 6;

FIGS. 7a through 7 c are cross-sectional views of the anatomicalstructure containing a catheter in accordance with the first embodimentof the invention and depicting the anatomical structure at variousstages of ligation;

FIG. 8 is a cross-sectional view of an anatomical structure containing acatheter in accordance with the second embodiment of the invention asdepicted in FIG. 4;

FIG. 8a is an end view of the anatomical structure containing thecatheter taken along line 8 a—8 a of FIG. 8;

FIGS. 9a and 9 b are cross-sectional views of the anatomical structurecontaining the catheter in accordance with the second embodiment of theinvention and depicting the anatomical structure at various stages ofligation;

FIG. 10 is a cross-sectional view of the working end of a thirdembodiment of a catheter in accordance with the invention depicting theelectrodes in a fully retracted position;

FIG. 10a is an end view of the working end of the third embodiment ofthe catheter taken along line 10 a—10 a of FIG. 10;

FIG. 11 is a cross-sectional view of the working end of the thirdembodiment depicting the electrodes in a fully expanded position;

FIG. 11a is an end view of the working end of the catheter taken alongline 11 a—11 a of FIG. 11;

FIG. 12 is a cross-sectional view of an anatomical structure containingthe catheter of FIG. 10 with the electrodes in apposition with theanatomical structure;

FIG. 13 is a cross-sectional view of the anatomical structure containingthe catheter of FIG. 10 where the anatomical structure is being ligatedby the application of energy from the electrodes;

FIG. 14 is a cross-sectional view of an anatomical structure containingthe catheter of FIG. 10 with the electrodes in apposition with theanatomical structure where external compression is being applied toreduce the diameter of the hollow structure before the application ofenergy from the electrodes to ligate the structure;

FIG. 15 is a side view of another embodiment of an electrode catheterhaving a balloon and a coaxial fluid channel;

FIG. 16 is a view of the balloon and catheter of FIG. 15 showing theballoon inflation ports formed in an inflation sheath of the catheter,also showing the inflation lumen that communicates with the inflationports;

FIG. 17 is a cross-sectional view of an anatomical structure containinganother embodiment of the catheter having a balloon located proximal tobowable arms with electrodes, the portion of the catheter distal to theballoon having perfusion holes;

FIG. 18 is a side view of another embodiment of an electrode catheterhaving a covering spanning the splayed leads of the electrodes extendedout the catheter;

FIG. 19 is a side view of another embodiment of an electrode catheterhaving a balloon and a coaxial fluid channel located proximal toexpandable leads, the balloon having openings for receiving blood tomaintain deployment of the balloon;

FIG. 20 is a side view of another embodiment of an electrode catheterhaving a balloon and a coaxial fluid channel located proximal toexpandable leads, the balloon having openings for receiving blood tomaintain deployment of the balloon;

FIG. 21 is a partial cross-sectional side view of another embodiment ofan electrode catheter having an expandable section which is covered by amembrane;

FIG. 22 is a partial cross-sectional side view of the embodiment of anelectrode catheter of FIG. 21 in an expanded condition;

FIG. 23 is a view of a catheter used in a method in accordance with theinvention to treat a hemorrhoid;

FIG. 24 is a view of a catheter used in a method in accordance with theinvention to treat an esophageal varix; and

FIG. 25 is a view of a catheter used in a method in accordance with theinvention for fallopian tube ligation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Turning now to the drawings with more particularity wherein likereference numerals indicate like or corresponding elements among thefigures, shown in FIG. 1 is a catheter 10 for applying energy to ananatomical structure such as a vein. The catheter 10 includes an outersheath 12 having a distal orifice 14 at its working end 15. Theconnector end 17 of the outer sheath 12 is attached to a handle 16 thatincludes an electrical connector 18 for interfacing with a power source22, typically an RF generator, and a microprocessor controller 23. Thepower source 22 and microprocessor 23 are usually contained in one unit.The controller 23 controls the power source 22 in response to externalcommands and data from a sensor, such as a thermocouple, located at anintraluminal venous treatment site. In another embodiment, the user canselect a constant power output so that automated temperature control isnot present and the user can manually adjust the power output in view ofthe temperature on a display readout. The catheter 10 includes anexpandable electrode device 24 (partially shown) that moves in and outof the outer sheath 12 by way of the distal orifice 14. The electrodedevice includes a plurality of electrodes which can be expanded bymoving the electrodes within the shaft, or by moving the outer shaftrelative to the electrodes. Although FIG. 1 illustrates a plurality ofelectrodes surrounding a single central electrode, different electrodeconfigurations will be described for the catheter.

Contained within the outer sheath 12 is an inner sheath 28 or innermember. A fluid port 21 communicates with the interior of the outersheath 12. The catheter 10 can be periodically flushed out with salinethrough the port 21. The flushing fluid can travel between the outersheath and the inner sheath. The port also allows for the delivery ofdrug therapies. Flushing out the catheter prevents the buildup ofbiological fluid, such as blood, within the catheter 10. The treatmentarea of the hollow anatomical structure such as a vein can be flushedwith a fluid such as saline, or a dielectric fluid, in order to evacuateblood from the treatment area of the vein so as to prevent the formationof coagulum or thrombosis. The use of a dielectric fluid can minimizeunintended heating effects away from the treatment area. The dielectricfluid prevents the current of RF energy from flowing away from the veinwall.

In one embodiment, the catheter 10 includes a lumen which begins at thedistal tip of the outer sheath 12 and runs substantially along the axisof the outer sheath 12 before terminating at the guide-wire port 20 ofthe handle 16. A guide wire can be introduced through the lumen of thecatheter 10 for use in guiding the catheter to the desired treatmentsite. Where the catheter is sized to treat smaller veins, the outerdiameter of the catheter may not allow for a fluid flush between theouter sheath 12 and the inner sheath 28. However, a fluid flush can beintroduced through the lumen for the guide wire in such an embodiment.

Referring now to FIGS. 2, 2 a, 3, 4, 4 a and 5, the outer sheath 12includes a shell 44 and a tip portion 46. To provide an atraumatic tipfor the catheter 10 as it is manipulated through the vein, the tip 46 ispreferably tapered inward at its distal end or is “nosecone” shaped. Thetip 46, however, can have other shapes that facilitate tracking of thecatheter 10 over a guide wire and through the bends in the venousvascular system. The nosecone-shaped tip 46 can, for example, befabricated from a polymer having a soft durometer, such as 70 Shore A.The shell 44 comprises a biocompatible material having a low coefficientof friction. In one configuration, the outer sheath 12 is sized to fitwithin a venous lumen and for example may be between 5 and 9 French,which corresponds to a diameter of between 1.7 mm (0.07 in) and 3.0 mm(1.2 in), or other sizes as appropriate.

The electrode device 24 contains a number of leads, including insulatedprimary leads 30 and, in some embodiments, a secondary lead 31.Preferably, the leads are connected to the power source 22 (FIG. 1) suchthat the polarity of the leads may be switched as desired. Alternately,a microprocessor controller can be used to switch the polarity, as wellas control other characteristics of the power for the electrode device.Thus the electrode device can operate in either a bipolar or a monopolarconfiguration. When adjacent primary leads 30 have opposite polarity theelectrode device 24 operates as a bipolar electrode device. When theprimary leads 30 are commonly charged the electrode device 24 canoperate as a monopolar electrode device. When the primary leads 30 arecommonly charged, and a secondary lead 31 has an opposite polarity, theelectrode device 24 operates as a bipolar electrode device. Theembodiment of the invention shown in FIGS. 2 and 3 depict an electrodedevice 24 having four primary leads 30 and a secondary lead 31, whilethe embodiment of the invention shown in FIGS. 4 and 5 depict anelectrode device 24 having only four primary leads. The invention is notlimited to four primary leads 30; more or fewer leads may be used ineither embodiment. The number of leads can be dependent on the size ordiameter of the hollow anatomical structure to be treated. The apposedelectrodes should be kept within a certain distance of one another.Larger vessels may require more primary leads to ensure proper currentdensity and proper heat distribution.

The insulation on each of the leads 30, 31 may be removed at the distalend 32, 33 to expose the conductive wire. In the first configuration asshown in FIGS. 2, 2 a, and 3, each electrode 34 has a hemisphericalshape. In a second configuration, the electrode can have either agenerally spherical shape or a spoon shape. As shown in FIGS. 4, 4 a and5, the electrodes have a spoon shape which can be combined to form asphere or other shape so as to minimize its profile when the veincollapses. The electrodes 34 are either integrally formed at the distalend 32, soldered, or otherwise formed to the distal end of each primarylead 30. It is to be understood that when the distal end 32 is referredto as acting as an electrode, this is not limited to where the electrode34 is integrally formed at the distal end 32. For example, the distalend can apply energy to the surrounding tissue where there is anelectrode integrally formed at the distal end, or where an electrode isseparately soldered to the distal end, or where there is another energydelivery device located at the distal end. The electrode 34 typicallyhas a diameter greater than the diameter of the primary lead 30. Forexample, the primary lead 30 may have a diameter ranging from 0.18 mm(0.007 in.) to 0.28 mm (0.011 in.), while the electrode 34 has adiameter of 0.36 mm (0.014 in.) to 0.51 mm (0.020 in.). The primaryleads 30 and the electrodes 34 are preferably made from abiologically-compatible material such as stainless steel. The insulationsurrounding the primary leads 30 generally has a thickness of between0.03 mm (0.001 in.) and 0.06 mm (0.0025 in.), resulting in a combinedlead-insulation diameter of between 0.23 mm (0.009 in.) and 0.41 mm(0.016 in.). In an alternate configuration, as shown in FIGS. 2 and 3,each primary lead 30 is strip-shaped with a width from 0.76 mm (0.03in.) to 1.0 mm (0.04 in) and a thickness of approximately 0.13 mm (0.005in.), while the secondary lead 31 is typically tubular-shaped. It shouldbe noted that these dimensions are provided for illustrative purposes,and not by way of limitation. A hemispherical electrode 34 is shaped atthe distal end, as for example, by sanding down a sixteenth-inch (1.6mm) diameter sphere which is soldered to the distal end 32 of theprimary lead 30. The electrodes can also be constructed by stamping thedesired shape or configuration from the conductive lead. The electrodeis integral with the lead, and the remainder of the lead is insulated.The distal end 33 of the secondary lead 31 preferably includes agenerally spherically-shaped electrode 35.

An alignment device 36 arranges the leads 30, 31 such that they aremounted to the catheter at only their proximal ends and so thatseparation is maintained between the leads within, and distal to thealignment device. The leads can form cantilevers when mounted on thealignment device. A preferred configuration of the alignment device 36includes a plurality of off-center, axially-aligned lumina 38 which aresubstantially symmetrically positioned relative to the axis of thealignment device 36. The alignment device 36 is formed, for example, byextruding the plurality of axially-aligned lumina 38 through a solidcylinder composed of a dielectric material, such as polyamide. Each lead30 passes through an individual off-center lumen 38 and exits out therear of the alignment device 36. The alignment device 36 may furtherinclude a central lumen 48 that may be aligned with the axis. In someembodiments the central lumen 48 is used for accepting a guide wire orfor the delivery or perfusion of medicant and cooling solution to thetreatment area during application of RF energy. In other embodiments,the central lumen 48 may be used for the secondary lead 31. Thealignment device 36 may also further include an auxiliary lumen 47 foradditional leads, such as the leads of a thermocouple used as atemperature sensor. The alignment device 36 comprises a dielectricmaterial to prevent or minimize any coupling effect the leads 30, 31 mayhave with each other and, if present, the guide wire. The length of thealignment device is, for example, 12.5 mm (0.5 in.) to 19.0 mm (0.75in.) in one embodiment. However, these dimensions are provided forpurposes of illustration and not by way of limitation.

In the embodiment of the invention shown in FIGS. 2, 2 a and 3, theinner sheath 28 is attached to the alignment device 36 and extendsbeyond the rear 37 of the alignment device. Preferably, the inner sheath28 completely surrounds the exterior wall of the alignment device 36 andis mounted to it by adhesive or press fit or in other manner such thatit remains in a fixed position relative to the inner sheath. The innersheath and alignment device can act as an inner member relative to theouter sheath. The inner sheath 28 comprises a biocompatible materialwith a low coefficient of friction. The inner sheath 28 provides apathway for the interconnection between the leads 30, 31 and theelectrical connector 18 (FIG. 1). This interconnection may occur in anyof several ways. The leads 30, 31 themselves may be continuous and runthe entire length of the inner sheath 28. In the alternative (notshown), the positively charged leads 30, 31 may couple with a commonpositively charged conductor housed in the inner sheath 28. Likewise,the negatively charged leads 30, 31 may couple with a common negativeconductor. Preferably, the leads 30, 31 are connected to a conductorthat allows for the polarity of the leads to be switched. The conductormay comprise, for example, a 36 gauge copper lead with a polyurethanecoating. The coupling may occur at any point within the inner sheath 28.To reduce the amount of wire contained in the catheter, it isadvantageous to couple the leads 30, 31 at the point where the leadsexit the rear 37 of the alignment device 36. To add further stability tothe electrode device 24, it is preferred that bonding material 40surround the leads 30, 31 at the front end of the alignment device 36.In this embodiment, the leads 30, 31 exit through the distal orifice 14as the outer sheath 12 is retracted backwards over the alignment device36. The inwardly tapered tip 46 impedes the retracting movement of theouter sheath 12 to prevent the exposure of the alignment device 36.

FIG. 3 shows the leads 30 and 31 in the retracted position where allleads are within the nosecone-shaped tip portion 46 and the outer shell44. The alignment device 36 has been moved relative to the outer shell44. The soft nosecone provides an atraumatic tip for when the catheteris maneuvered through the tortuous venous system. The electrode at thedistal end of the secondary lead 31 can be sized to approximately thesame size as the opening formed in the nosecone 46. The nosecone forms aclosed atraumatic tip together with the electrode of the secondary leadwhen the alignment device is retracted into the outer sheath of thecatheter. This can present an atraumatic tip even where the nosecone isnot constructed from a material having a soft durometer.

Referring now to FIGS. 4 and 5, in another embodiment, the alignmentdevice 36 is attached to the outer sheath 12 and thereby remainsimmobile in relation to it. The inner sheath 28 is movably positioned atthe rear of the alignment device 36 and again provides a pathway for theinterconnection between the primary leads 30 and the electricalconnector 18 (FIG. 1). In some embodiments the inner sheath 28 containsa guide-wire tube 49 that runs the entire length of the inner sheath.The guide-wire tube 49 is aligned to communicate with the central lumen48 of the alignment device 36 at one end and with the guide-wire port 20(FIG. 1) at the other end. The primary leads 30 may be continuous andrun the entire length of the inner sheath 28 or they may be coupled tocommon leads as previously described. The primary leads 30 are securedto the front end 27 of the inner sheath 28, as for example with apotting material 50, so that the movement of the inner sheath 28 resultsin a corresponding movement of the primary leads 30 through the lumina38 of the alignment device 36. In this embodiment, the primary leads 30are not secured to the alignment device 36 and in essence arefree-floating leads in the axial direction. The primary leads 30 travelthrough the alignment device 36 and exit through the distal orifice 14as the front end of the inner sheath 28 is moved toward the rear 37 ofthe alignment device 36.

In the above embodiments, the primary leads 30 are formed, e. g., arcedor bent, to move away from each other and thereby avoid contact. The“distal portion” of the primary leads 30 is the portion of the leadwhich extends from the front end of the alignment device 36 when theleads are fully extended through the distal orifice 14. It is preferredthat the distal portions 42 are formed to move radially outward fromeach other relative to the axis of the alignment device 36 and form asymmetrical arrangement. This is shown in both the embodiments of FIG.2a and FIG. 4a. The degree of arc or bend in the primary leads 30 may beany that is sufficient to radially expand the leads as they exit theouter sheath 12 through the distal orifice 14. It is essential that thedegree of the arc or bend be sufficient to provide enough force so thatthe primary leads 30 expand through blood and the electrodes 34 come inapposition with the vein wall. The electrodes are preferably partiallyembedded in the vein wall to assure full contact. The rounded portion ofthe electrode is embedded into the vein wall to achieve full surfaceapposition so that the entire uninsulated surface area of the electrodeis in contact with venous tissue for effective current distribution. Thesurface area of the electrodes in contact with the venous tissuepreferably is sufficient to avoid a high current density which may leadto spot heating of the venous tissue. The heating effect is preferablydistributed along a circumferential band of the vein. The apposedelectrodes should be spaced no more than 4 or 5 millimeters from oneanother along the circumference of the vein. Thus, the electrodearrangement is related to the size or diameter of the vein beingtreated. Other properties of the primary leads 30, such as lead shapeand insulation thickness, affect the push force of the lead and thedegree of arc or bend must be adjusted to compensate for these factors.For example, in one configuration of the electrode device 24, a wirehaving a diameter of between 0.18 mm (0.007 in) and 0.28 mm (0.011 in)with a total insulation thickness of between 0.05 mm (0.002 in) to 0.13mm (0.005 in) is arced or bent at an acute angle to provide sufficientapposition with the anatomical structure. It is to be understood thatthese dimensions are provided for illustrative purposes, and not by wayof limitation.

Other techniques for expanding the leads outwardly once they have beenextended from the working end of the catheter may be possible. Forexample, the leads may be straight but are mounted in the alignmentdevice at an angle such that they are normally directed outward.

For increased appositional force, it is preferred that the primary leads30 be strip-shaped, that is rectangular in cross section, withdimensions, for example, of a width from 0.76 mm (0.030 in.) to 1.0 mm(0.039 in) and a thickness of approximately 0.13 mm (0.005 in.). Therectangular cross section provides increased resistance to bending inthe width dimension but allows bending more freely in the thicknessdimension. This strip-shaped configuration of the primary leads 30 isshown in FIGS. 2, 2 a, and 3 and provides for increased stability in thelateral direction while allowing the necessary bending in the radialdirection. In FIGS. 2, 2 a, and 3, each primary lead comprises arectangular cross section mounted in relation to the catheter such thatthe thinner dimension of the rectangular cross section is aligned withthe direction of expansion of the lead. The leads are less likely tobend sideways when expanded outward, and a uniform spacing between leadsis more assured. Uniform spacing promotes uniform heating around thevenous tissue which is in apposition with the electrodes at the distalends of the leads.

The length of the distal portion of the leads 30 also affects theconfiguration of the electrode device 24. The maximum distance betweentwo mutually opposed electrodes 34; i.e., the effective diameter of theelectrode device 24, is affected by the bend degree and length of thedistal portion 42. The longer the length of the distal portion 42 thegreater the diameter of the electrode device 24. Accordingly, bychanging the distal portion 42 length and arc or bend degree, thecatheter 10 can be configured for use in differently sized anatomicalstructures.

Different numbers of leads 30, 31 can be employed with the catheter. Thenumber of leads 30, 31 is limited by the diameter of the alignmentdevice 36 and the number of lumina 36, 38, 47 that can be extrudedthrough the alignment device. In a bipolar configuration, an even numberof primary leads 30 are preferably available to form a number ofoppositely charged electrode pairs. The electrodes in apposition withthe anatomical structure should be maintained within a certain distanceof each other. In a monopolar configuration, any number of commonlycharged leads 30 can be present. In the monopolar mode, distribution ofRF energy through the anatomical tissue is obtained by creating a returnpath for current through the tissue by providing a return device at apoint external from the tissue, such as a large metal pad.

Now referring again to FIG. 1, an actuator 25 controls the extension ofthe electrode device 24 through the distal orifice 14. The actuator 25may take the form of a switch, lever, threaded control knob, or othersuitable mechanism, and is preferably one that can provide fine controlover the movement of the outer sheath 12 or the inner sheath 28, as thecase may be. In one embodiment of the invention, the actuator 25(FIG. 1) interfaces with the outer sheath 12 (FIG. 2, 2 a and 3) to moveit back and forth relative to the inner sheath 28. In another embodimentthe actuator 25 (FIG. 1) interfaces with the inner sheath 28 (FIGS. 4, 4a and 5) to move it back and forth relative to the outer sheath 12. Therelative position between the outer sheath and inner sheath is thuscontrolled, but other control approaches may be used.

Referring again to FIGS. 2, 2 a, 3, 4, 4 a and 5, the catheter 10includes a temperature sensor 26, such as a thermocouple. Thetemperature sensor 26 is mounted in place on an electrode 34 so that thesensor 26 is nearly or is substantially flush with the exposed surfaceof the electrode 34. The sensor 26 is shown in the drawings asprotruding from the electrodes for clarity of illustration only. Thesensor 26 senses the temperature of the portion of the anatomical tissuethat is in apposition with the exposed electrode surface. Monitoring thetemperature of the anatomical tissue provides a good indication of whenshrinkage of the tissue is ready to begin. A temperature sensor 26placed on the electrode facing the anatomical tissue provides anindication of when shrinkage occurs (70° C. or higher) and whensignificant amounts of heat-induced coagulum may begin to form on theelectrodes. Therefore maintaining the temperature above 70 degreesCentigrade produces a therapeutic shrinkage of the anatomical structure.Application of the RF energy from the electrodes 34 is halted or reducedwhen the monitored temperature reaches or exceeds the specifictemperature that was selected by the operator, typically the temperatureat which anatomical tissue begins to cauterize. The temperature sensor26 interfaces with the controller 23 (FIG. 1) through a pair of sensorleads 45 which preferably run through the auxiliary lumen 47 and thenthrough the inner sheath 28. The signals from the temperature sensor 26are provided to the controller 23 which controls the magnitude of RFenergy supplied to the electrodes 34 in accordance with the selectedtemperature criteria and the monitored temperature. Other techniquessuch as impedance monitoring, and ultrasonic pulse echoing can beutilized in an automated system which shuts down or regulates theapplication of RF energy from the electrodes to the venous section whensufficient shrinkage of the vein is detected and to avoid overheatingthe vein. Impedance can be used to detect the onset of coagulumformation.

Referring now to FIGS. 6, 6 a and 7 a through 7 c, in the operation ofone embodiment of the catheter 10, the catheter is inserted into ahollow anatomical structure, such as a vein 52. The catheter is similarto the embodiment discussed in connection with FIGS. 2 and 3. Thecatheter 10 further includes an external sheath 60 through which a fluidcan be delivered to the treatment site. In this embodiment, the fluidport (not shown) communicates with the interior of the external sheath60, and fluid is delivered from between the external sheath 60 and theouter sheath 12. The external sheath 60 surrounds the outer sheath 12 toform a coaxial channel through which fluid may be flushed.

Fluoroscopy, ultrasound, an angioscope imaging technique, or othertechnique may be used to direct the specific placement of the catheterand confirm the position in the vein. The actuator (not shown) is thenoperated to shift the outer sheath relative to the inner sheath byeither retracting the outer sheath 12 backward or advancing the innersheath 28 forward to expose the leads 30, 31 through the distal orifice14. As the leads 30, 31 exit the distal orifice 14, the primary leads 30expand radially outward relative to the axis of the alignment device 36,while the secondary lead 31 remains substantially linear. The primaryleads 30 continue to move outward until apposition with the vein wall 54occurs and the outward movement of the primary leads 30 is impeded. Theprimary leads 30 contact the vein along a generally circumferential bandof the vein wall 54. This outward movement of the primary leads 30occurs in a substantially symmetrical fashion. As a result, theprimary-lead electrodes 34 are substantially evenly spaced along thecircumferential band of the vein wall 54. The central-lead electrode 35is suspended within the vein 52 without contacting the vein wall 54.

When the electrodes 34 are positioned at the treatment site of the vein,the power supply 22 is activated to provide suitable RF energy. Onesuitable frequency is 510 kHz. One criterion used in selecting thefrequency of the energy to be applied is the control desired over thespread, including the depth, of the thermal effect in the venous tissue.Another criterion is compatibility with filter circuits for eliminatingRF noise from thermocouple signals.

In bipolar operation, the primary leads 30 are initially charged suchthat adjacent leads are oppositely charged while the secondary lead iselectrically neutral. These multiple pairs of oppositely charged leads30 form active electrode pairs to produce an RF field between them.Thus, discrete RF fields are set up along the circumferential band ofthe vein wall 54. These discrete fields form a symmetrical RF fieldpattern along the entire circumferential band of the vein wall 54, asadjacent electrodes 34 of opposite polarity produce RF fields betweeneach other. A uniform temperature distribution can be achieved along thevein wall being treated.

The RF energy is converted within the adjacent venous tissue into heat,and this thermal effect causes the venous tissue to shrink, reducing thediameter of the vein. A uniform temperature distribution along the veinwall being treated avoids the formation of hot spots in the treatmentarea while promoting controlled uniform reduction in vein diameter. Thethermal effect produces structural transfiguration of the collagenfibrils in the vein. The collagen fibrils shorten and thicken incross-section in response to the heat from the thermal effect. As shownin FIG. 7a, the energy causes the vein wall 54 to collapse around theprimary-lead electrodes 34. The wall 54 continues to collapse untilfurther collapse is impeded by the electrodes 34. The electrodes arepressed farther and farther together by the shrinking vein wall 54 untilthey touch and at that point, further collapse or ligation of the wall54 is impeded. Upon collapse of the vein wall 54 around the primary-leadelectrodes 34, the polarity of the primary-lead electrodes is switchedso that all primary-lead electrodes are commonly charged. The switchingof polarity for the leads need not be instantaneous. The application ofRF energy can be ceased, the polarity switched, and then RF energy isapplied again at the switched polarity. The secondary-lead electrode 35is then charged so that its polarity is opposite that of theprimary-lead electrodes 34. The RF field is set up between theprimary-lead electrodes 34 and the secondary-lead electrode 35.

The catheter 10 is then pulled back while energy is applied to theelectrode device. As shown in FIG. 7b, while the catheter 10 is beingpulled back, the primary-lead electrodes 34 remain in apposition withthe vein wall 54 while the secondary-lead electrode 35 comes in contactwith the portion of the vein wall previously collapsed by theprimary-lead electrodes 34. Accordingly, RF energy passes through thevein wall 54 between the primary-lead electrodes 34 and thesecondary-lead electrode 35 and the vein wall continues to collapsearound the secondary-lead electrode 35 as the catheter 10 is beingretracted. As shown in FIG. 7c, ligation in accordance with this methodresults in an occlusion along a length of the vein 52. A lengthyocclusion, as opposed to an acute occlusion, is stronger and lesssusceptible to recanalization.

A similar result is achieved when the catheter 10 having both primaryand secondary leads is operated in a monopolar manner. In a monopolaroperation, the secondary-lead electrode 35 remains neutral, while theprimary leads 30 are commonly charged and act in conjunction with anindependent electrical device, such as a large low-impedance return pad(not shown) placed in external contact with the body, to form a seriesof discrete RF fields. These RF fields are substantially evenly spacedaround the circumference of the vein and travel along the axial lengthof the vein wall causing the vein wall to collapse around theprimary-lead electrodes. Upon collapse of the vein wall, thesecondary-lead electrode is charged to have the same polarity as that ofthe primary-lead electrodes. The electrode device is retracted and thevein wall collapses as described in the bipolar operation.

In either bipolar or monopolar operation the application of RF energy issubstantially symmetrically distributed through the vein wall,regardless of the diameter of the vein 52. This symmetrical distributionof RF energy increases the predictability and uniformity of theshrinkage and the strength of the occlusion. Furthermore, the uniformdistribution of energy allows for the application of RF energy for ashort duration and thereby reduces or avoids the formation ofheat-induced coagulum on the electrodes 34. The leads, including thenon-convex outer portion of the electrode, are insulated to furtherprevent heating of the surrounding blood.

Fluid can be delivered before and during RF heating of the vein beingtreated through a coaxial channel formed between the external sheath 60and the outer sheath 12. It is to be understood that another lumen canbe formed in the catheter to deliver fluid to the treatment site. Thedelivered fluid displaces or exsanguinates blood from the vein so as toavoid heating and coagulation of blood. Fluid can continue to bedelivered during RF treatment to prevent blood from circulating back tothe treatment site. The delivery of a dielectric fluid increases thesurrounding impedance so that RF energy is directed into the tissue ofthe vein wall.

Referring now to FIGS. 8, 8 a, 9 a and 9 b, in the operation of analternate embodiment of the catheter 10 that may be used with a guidewire 53. As in the previous embodiment, the catheter 10 is inserted intoa hollow anatomical structure, such as a vein 52. The guide wire 53 isadvanced past the point where energy application is desired. Thecatheter 10 is then inserted over the guide wire 53 by way of thecentral lumen 48 and the guide wire tube 49 (FIG. 4) and is advancedover the guide wire through the vein to the desired point. The guidewire 53 is typically pulled back or removed before RF energy is appliedto the electrode device 24.

The actuator 25 (FIG. 1) is then manipulated to either retract the outersheath 12 backward, or advance the inner sheath 28 forward to expose theleads 30 through the distal orifice 14. The leads 30 exit the distalorifice 14 and expand radially outward relative to the axis of thealignment device 36. The leads 30 continue to move outward untilapposition with the vein wall 54 occurs. The leads 30 contact the veinalong a generally circumferential band of the vein wall 54. This outwardmovement of the leads occurs in a substantially symmetrical fashion. Asa result, the electrodes 34 are substantially evenly spaced along thecircumferential band of the vein wall 54. Alternately, the electrodescan be spaced apart in a staggered fashion such that the electrodes donot lie along the same plane. For example, adjacent electrodes canextend different lengths from the catheter so that a smallercross-sectional profile is achieved when the electrodes are collapsedtoward one another.

When the electrodes 34 are positioned at the treatment site of the vein,the power supply 22 is activated to provide suitable RF energy to theelectrodes 34 so that the catheter 10 operates in either a bipolar ormonopolar manner as previously described. As shown in FIGS. 9a and 9 b,the energy causes the vein wall 54 to collapse around the electrodes 34causing the leads to substantially straighten and the electrodes tocluster around each other. The wall 54 continues to collapse untilfurther collapse is impeded by the electrodes 34 (FIG. 9b). At thispoint the application of energy may cease. The electrodes can beconfigured to form a shape with a reduced profile when collapsedtogether. The electrodes can also be configured and insulated tocontinue applying RF energy after forming a reduced profile shape by thecollapse of the vein wall. The catheter 10 can be pulled back to ligatethe adjacent venous segment. If a temperature sensor 26 is included, theapplication of energy may cease prior to complete collapse if thetemperature of the venous tissue rises above an acceptable level asdefined by the controller 23.

Where the catheter includes a fluid delivery lumen (not shown), fluidcan be delivered before and during RF heating of the vein being treated.The fluid can displace blood from the treatment area in the vein toavoid the coagulation of blood. The fluid can be a dielectric medium.The fluid can include an anticoagulant such as heparin which canchemically discourage the coagulation of blood at the treatment site.

After completing the procedure for a selected venous section, theactuator mechanism causes the primary leads to return to the interior ofthe outer sheath 12. Either the outer sheath or the inner sheath ismoved to change the position of the two elements relative to oneanother. Once the leads 30 are within the outer sheath 12, the catheter10 may be moved to another venous section where the ligation process isrepeated. Upon treatment of all venous sites, the catheter 10 is removedfrom the vasculature. The access point of the vein is then suturedclosed, or local pressure is applied until bleeding is controlled.

Another embodiment of the catheter is illustrated in FIG. 10. The innermember or sheath 28 is contained within the outer sheath 12. The innersheath is preferably constructed from a flexible polymer such aspolyimide, polyethylene, or nylon, and can travel the entire length ofthe catheter. The majority of the catheter should be flexible so as tonavigate the tortuous paths of the venous system. A hypotube having aflared distal end and a circular cross-sectional shape is attached overthe distal end of the inner sheath 28. The hypotube is preferably nomore than about two to three centimeters in length. The hypotube acts aspart of the conductive secondary lead 31. An uninsulated conductiveelectrode sphere 35 is slipped over the hypotube. The flared distal endof the hypotube prevents the electrode sphere from moving beyond thedistal end oft he hypotube. The sphere is permanently affixed to thehypotube, such as by soldering the sphere both front and back on thehypotube. The majority or the entire surface of the spherical electrode35 remains uninsulated. The remainder of the hypotube is preferablyinsulated so that the sphere-shaped distal end can act as the electrode.For example, the hypotube can be covered with an insulating materialsuch as a coating of parylene. The interior lumen of the hypotube islined by the inner sheath 28 which is attached to the flaired distal endof the hypotube by adhesive such as epoxy.

Surrounding the secondary lead 31 and sphere-shaped electrode 35 are aplurality of primary leads 30 which preferably have a flat rectangularstrip shape and can act as arms. As illustrated in FIG. 11, theplurality of primary leads are preferably connected to common conductiverings 62. This configuration maintains the position of the plurality ofprimary leads, while reducing the number of internal electricalconnections. The rings 62 are attached to the inner sheath 28. Theposition of the rings and the primary leads relative to the outer sheathfollows that of the inner sheath. As earlier described, the hypotube ofthe secondary lead 31 is also attached to the inner sheath 28. Twoseparate conductive rings can be used so that the polarity of differentprimary leads can be controlled separately. For example, adjacentprimary leads can be connected to one of the two separate conductiverings so that the adjacent leads can be switched to have either oppositepolarities or the same polarity. The rings are preferable spaced closelytogether, but remain electrically isolated from one another along theinner sheath. Both the rings and the hypotube are coupled with the innersheath, and the primary leads 30 that are connected to the rings movetogether with and secondary lead while remaining electrically isolatedfrom one another. Epoxy or another suitable adhesive can be used toattach the rings to the inner sheath. The primary leads from therespective rings each alternate with each other along the circumferenceof the inner sheath. The insulation along the underside of the leadsprevents an electrical short between the rings.

The ring and primary leads are attached together to act as cantileverswhere the ring forms the base and the rectangular primary leads operateas the cantilever arms. The leads 30 are connected to the ring and areformed to have an arc or bend such that the leads act as arms which tendto spring outwardly away from the catheter and toward the surroundingvenous tissue. Insulation along the underside of the leads and the ringsprevents unintended electrical coupling between the leads and theopposing rings. Alternately, the leads are formed straight and connectedto the ring at an angle, such that the leads tend to expand or springradially outward from the ring. The angle at which the leads areattached to the ring should be sufficient to force the primary distalends and electrodes 34 through blood and into apposition with the veinwall. Other properties of the primary leads 30, such as lead shape andinsulation thickness, affect the push force of the lead and the degreeof arc or bend must be adjusted to compensate for these factors. Therectangular cross section of the leads 30 can provide increasedstability in the lateral direction while allowing the necessary bendingin the radial direction. The leads 30 are less likely to bend sidewayswhen expanded outward, and a uniform spacing between leads is moreassured. Uniform spacing between the leads 30 and the distal endspromotes uniform heating around the vein by the electrodes 34.

The distal ends of the primary leads 30 are uninsulated to act aselectrodes 34 having a spoon or hemispherical shape. The leads can bestamped to produce an integral shaped electrode at the distal end of thelead. The uninsulated outer portion of the distal end electrode 34 whichis to come into apposition with the wall of the anatomical structure ispreferably rounded and convex. The flattened or non-convex inner portionof the distal end is insulated to minimize any unintended thermaleffect, such as on the surrounding blood in a vein. The distal endelectrodes 34 are configured such that when the distal ends are forcedtoward the inner sheath 12, as shown in FIG. 10a, the distal endscombine to form a substantially spherical shape with a profile smallerthan the profile for the spherical electrode 35 at the secondary distalend.

The outer sheath 12 can slide over and surround the primary andsecondary leads 30, 31. The outer sheath 12 includes an orifice which isdimensioned to have approximately the same size as the sphericalelectrode 35 at the secondary distal end which functions as anelectrode. A close or snug fit between the electrode 35 at the secondarydistal end and the orifice of the outer sheath 12 is achieved. Thisconfiguration provides an atraumatic tip for the catheter. The electrode35 secondary distal end is preferably slightly larger than the orifice.The inner diameter of the outer sheath 12 is approximately the same asthe reduced profile of the combined primary distal end electrodes 34.The diameter of the reduced profile of the combined primary distal endelectrodes 34 is preferably less than the inner diameter of the outersheath.

A fluid port (not shown) can communicate with the interior of the outersheath 12 so that fluid can be flushed between the outer sheath 12 andthe inner sheath 28. Alternately, a fluid port can communicate with acentral lumen 48 in the hypotube which can also accept a guide wire. Aspreviously stated, the catheter 10 can be periodically flushed withsaline which can prevent the buildup of biological fluid, such as blood,within the catheter 10. A guide wire can be introduced through the lumen48 for use in guiding the catheter to the desired treatment site. Aspreviously described, a fluid can be flushed or delivered though thelumen as well. If a central lumen is not desired, the lumen of thehypotube can be filled with solder.

Preferably, the primary leads 30 and the connecting rings are connectedto a power source 22 such that the polarity of the leads may be switchedas desired. This allows for the electrode device 24 to operate in eithera bipolar or a monopolar configuration. When adjacent primary leads 30have opposite polarity, a bipolar electrode operation is available. Whenthe primary leads 30 are commonly charged a monopolar electrodeoperation is available in combination with a large return electrode padplaced in contact with the patient. When the primary leads 30 arecommonly charged, and a secondary lead 31 has an opposite polarity, abipolar electrode operation is available. More or fewer leads may beused. The number of leads can be dependent on the size or diameter ofthe hollow anatomical structure to be treated.

Although not shown, it is to be understood that the catheter 10 caninclude a temperature sensor, such as a thermocouple, mounted in placeon the distal end or electrode 34 so that the sensor is substantiallyflush with the exposed surface of the electrode 34. The sensor sensesthe temperature of the portion of the anatomical tissue that is inapposition with the exposed electrode surface. Application of the RFenergy from the electrodes 34 is halted or reduced when the monitoredtemperature reaches or exceeds the specific temperature that wasselected by the operator, such as the temperature at which anatomicaltissue begins to cauterize. Other techniques such as impedancemonitoring, and ultrasonic pulse echoing can be utilized in an automatedsystem which shuts down or regulates the application of RF energy fromthe electrodes to the venous section when sufficient shrinkage of thevein is detected and to avoid overheating the vein.

Referring now to FIGS. 12 through 14, in the operation of one embodimentof the catheter 10, the catheter is inserted into a hollow anatomicalstructure, such as a vein. Fluoroscopy, ultrasound, an angioscopeimaging technique, or another technique may be used to direct andconfirm the specific placement of the catheter in the vein. The actuatoris then operated to retract the outer sheath 12 to expose the leads 30,31. As the outer sheath no longer restrains the leads, the primary leads30 move outward relative to the axis defined by the outer sheath, whilethe secondary lead 31 remains substantially linear along the axisdefined by the outer sheath. The primary leads 30 continue to moveoutward until the distal end electrode 34 of the primary leads areplaced in apposition with the vein wall 54 occurs and the outwardmovement of the primary leads 30 is impeded. The primary leads 30contact the vein along a generally circumferential area of the vein wall54. This outward movement of the primary leads 30 occurs in asubstantially symmetrical fashion so that the primary distal endelectrodes 34 are substantially evenly spaced. The central-leadelectrode 35 is suspended within the vein without contacting the veinwall 54.

When the electrodes 34 are positioned at the treatment site of the vein,the power supply 22 is activated to provide suitable RF energy. In abipolar operation, the primary leads 30 are initially charged such thatadjacent leads are oppositely charged while the secondary lead iselectrically neutral. These multiple pairs of oppositely charged leads30 form active electrode pairs to produce an RF field between them, andform a symmetrical RF field pattern along a circumferential band of thevein wall to achieve a uniform temperature distribution along the veinwall being treated.

The RF energy produces a thermal effect which causes the venous tissueto shrink, reducing the diameter of the vein. As shown in FIG. 13, theenergy causes the vein wall 54 to collapse until further collapse isimpeded by the electrodes 34. The electrodes are pressed closer togetherby the shrinking vein wall. The electrodes 34 are pressed together toassume a reduced profile shape which is sufficiently small so that thevein is effectively ligated. Upon collapse of the vein wall 54 aroundthe primary-lead electrodes 34, the polarity of the primary-leadelectrodes is switched so that all of the primary-lead electrodes arecommonly charged. The secondary-lead electrode 35 is then charged sothat its polarity is opposite that of the primary-lead electrodes 34.Where the primary electrodes 34 and the secondary electrode 35 arespaced sufficiently close together, when the vein wall collapses aroundthe primary lead electrodes, the electrode at the distal end of thesecondary lead can also come into contact with the a portion of the veinwall so that an RF field is created between the primary electrodes 34and the secondary electrode 35.

The catheter 10 is pulled back to ensure apposition between theelectrodes at the distal ends of the leads and the vein wall. When thecatheter 10 is being pulled back, the primary-lead electrodes 34 remainin apposition with the vein wall 54 while the secondary-lead electrode35 comes in contact with the portion of the vein wall previouslycollapsed by the primary-lead electrodes 34. RF energy passes throughthe venous tissue between the primary-lead electrodes 34 and thesecondary-lead electrode 35. Ligation as the catheter is being retractedproduces a lengthy occlusion which is stronger and less susceptible torecanalization than an acute point occlusion.

In a monopolar operation, the secondary-lead electrode 35 remainsneutral, while the primary leads 30 are commonly charged and act inconjunction with an independent electrical device, such as a largelow-impedance return pad (not shown) placed in external contact with thebody, to form RF fields substantially evenly spaced around thecircumference of the vein. The thermal effect produced by those RFfields along the axial length of the vein wall causes the vein wall tocollapse around the primary-lead electrodes. Upon collapse of the veinwall, the secondary-lead electrode is charged to have the same polarityas that of the primary-lead electrodes. The electrode device isretracted as described in the bipolar operation.

In either bipolar or monopolar operation the application of RF energy issubstantially symmetrically distributed through the vein wall. Aspreviously described, the electrodes should be spaced no more than 4 or5 millimeters apart along the circumference of the vein, which definesthe target vein diameter for a designed electrode catheter. Where theelectrodes are substantially evenly spaced in a substantiallysymmetrical arrangement, and the spacing between the electrodes ismaintained, a symmetrical distribution of RF energy increases thepredictability and uniformity of the shrinkage and the strength of theocclusion.

As shown in FIG. 14, after the electrodes 34 come into apposition withthe vein wall (FIG. 12), and before the energy is applied to ligate thevein (FIG. 13), an external tourniquet, such as an elastic compressivewrap or an inflatable bladder with a window transparent to ultrasound,is used to compress the anatomy, such as a leg, surrounding thestructure to reduce the diameter of the vein. Although the compressiveforce being applied by the tourniquet may effectively ligate the vein,or otherwise occlude the vein by flattening the vein, for certain veins,this compressive force will not fully occlude the vein. A fixed diameterelectrode catheter in this instance would not be effective. Theelectrodes 34 which are expanded outward by the formed leads 30 canaccommodate this situation.

The reduction in vein diameter assists in pre-shaping the vein toprepare the vein to be molded to a ligated state. The use of an externaltourniquet or elastic bandage also exsanguinates the vein and blood isforced away from the treatment site. Coagulation of blood duringtreatment can be avoided by this procedure. Energy is applied from theelectrodes to the exsanguinated vein, and the vein is molded to asufficiently reduced diameter to achieve ligation. The externaltourniquet or elastic bandage can remain in place to facilitate healing.

The catheter can be pulled back during the application of RF energy toligate an extensive section of a vein. In doing so, instead of a singlepoint where the diameter of the vein has been reduced, an extensivesection of the vein has been painted by the RF energy from the catheter.Retracting the catheter in this manner produces a lengthy occlusionwhich is less susceptible to recanalization. The combined use of theprimary and secondary electrodes can effectively produce a reduceddiameter along an extensive length of the vein. The catheter can bemoved while the tourniquet is compressing the vein, of after thetourniquet is removed.

Where the catheter includes a fluid delivery lumen, fluid can bedelivered to the vein before RF energy is applied to the vein. Thedelivered fluid displaces blood from the treatment site to ensure thatblood is not present at the treatment site, even after the tourniquetcompresses the vein.

Where the tourniquet is an inflatable bladder with a window transparentto ultrasound, an ultrasound transducer is used to monitor theflattening or reduction of the vein diameter from the compressive forcebeing applied by the inflating bladder. The window can be formed frompolyurethane, or a stand-off of gel contained between a polyurethanepouch. A gel can be applied to the window to facilitate ultrasoundimaging of the vein by the transducer. Ultrasound visualization throughthe window allows the operator to locate the desired venous treatmentarea, and to determine when the vein has been effectively ligated oroccluded. Ultrasound visualization assists in monitoring any pre-shapingof the vein in preparation of being molded into a ligated state by thethermal effect produced by the RF energy from the electrodes.

After completing the procedure for a selected venous section, theactuator causes the leads 30 to return to the interior of the outersheath 12. Once the leads 30 are within the outer sheath 12, thecatheter 10 may be moved to another venous section where the ligationprocess is repeated.

In another embodiment, as illustrated in FIG. 15, a balloon 64 islocated on the catheter, and can be inflated through ports 66 to occludethe vein. The inflated balloon obstructs blood flow and facilitates theinfusion of a high-impedance fluid to the vein in order to reduce theoccurrence of coagulation by directing the energy into the vein wall.The inflation of the balloon to occlude the vein before the applicationof energy can obviate the use of the tourniquet to occlude the vein.Furthermore, this also allows the vein to be occluded even for the deepveins where a compressive tourniquet may not be able to compress thevein to occlusion. It is to be understood that other mechanisms can beused to expand the diameter of the catheter to create an impermeablebarrier that occludes the vein.

Fluid 61 can be delivered after inflation of the balloon 64 and beforethe RF heating of the vein being treated through a coaxial channel 62formed between the external sheath 60 and the outer sheath 12. It is tobe understood that another lumen can be formed in the catheter todeliver fluid to the treatment site. For example, the lumen throughwhich the guide wire is passed may be used for the delivery of fluid.The delivered fluid displaces or exsanguinates the remaining blood fromthe treatment area of the vein so as to avoid heating and coagulation ofblood. Fluid can continue to be delivered during RF treatment to preventblood from circulating back to the treatment site. The delivery of ahigh-dielectric fluid increases the surrounding impedance so that RFenergy is directed into the tissue of the vein wall. Less energy is usedbecause the energy is directed to the target; i.e., the vein wall,rather than being dissipated in the blood. Therefore, the vein wall canreach the desired temperature more rapidly than in the case where energyis permitted to reach the blood, which has a cooling effect.Additionally, blood clotting is avoided with this approach, because theblood has been replaced with another fluid such as deionized water mixedwith heparin to displace blood and prevent the formation of blood clots.

A partial cross-sectional view of this embodiment is shown in FIG. 16,where an inflation sheath 70 surrounds the external sheath 60 to providea coaxial inflation lumen 72 for the balloon 64. The inflation lumen 72is in fluid communication with the ports 66. Saline or any othersuitable fluid can be used to inflate the balloon.

As shown in the FIG. 17, in one embodiment, the balloon 64 can be usedin combination with bowable members or arms 76 having electrodes, whereperfusion holes 78 are formed in the catheter between the balloon 64 andthe bowable arms 76. The balloon 64 in this embodiment is inflatedthrough a balloon inflation lumen 72 (as shown in FIG. 16). The use ofbowable arms for treating veins is discussed in U.S. patent applicationSer. No. 08/610,911, which is hereby incorporated by reference. The armscan be constructed so as to spring radially outward from the catheter,yet offer little resistance in moving back toward the catheter as thevein diameter is diminished to occlusion. An anti-coagulant or saline ora high-impedance fluid can be introduced or flushed through theperfusion holes 78 in the catheter. As discussed earlier, thehigh-impedance fluid forces blood away from the venous treatment areaand prevents the energy from being dissipated in a more conductivemedium such as blood.

As shown in FIG. 18, in another embodiment, a flexible covering 80 iswrapped around or inside the leads 30 of the electrodes 34 to preventblood flow in the vein. The covering 80 spans the area between thesplayed leads along the circumference of the catheter when the leads areextended out the opening, such that the webbed covering blocks bloodflow within the vein. The covering may be thought of as webbing or anumbrella to keep blood on one side away from the electrodes. When theelectrodes come into apposition with the vein wall, then the gap, ifany, between the electrodes 34 and the covering 80 should be eliminatedor otherwise minimized. The covering 80 should be impermeable to fluid.Suitable materials include PET and nylon. Elastomeric materials are alsosuitable as the leads will need to move close together as they areretracted, and interference with the movement of the leads as the veindiameter is reduced by the application of energy is preferablyminimized. Although this embodiment is illustrated with only primaryleads, it is to be understood that this embodiment is not so limited andthat a secondary lead may be included with the catheter as well withoutaffecting the use of the covering.

As with the balloon disclosed earlier, the covering occludes the veinbefore the application of energy, such that the need for an externalcompressive tourniquet is not required to stop blood flow. Furthermore,this also allows the vein to be occluded even for the deep veins where acompressive tourniquet may not be able to compress the vein toocclusion. A high-impedance fluid such as deionized water, or ananti-coagulant such as heparin or saline, or both, or heparin withdeionized water may be infused or flushed through a central lumen (notshown) similar to that shown in FIG. 4 as numeral 48 or to that shown inFIGS. 10 and 11 before the application of energy as well. The electrodesextend through the shaft lumen which also acts as a conduit for thefluid being flushed through a central lumen 48 (not shown). A sclerosingfluid may also be delivered to the venous treatment site to enhance theligation effect from the application of RF energy. The sclerosing fluidmay be added in addition to, or in substitution of, the previouslydiscussed fluids.

In the embodiment shown in FIG. 19, a covering 80 having a parachuteshape can be oriented so that blood becomes trapped by the concaveportion of the covering 80 and the volume of the blood maintains thedeployment of the covering. In this example, the covering is a balloonhaving openings which allow blood to gather in the balloon, and expandthe balloon. The covering 80 can be permanently attached to the cathetershaft. The catheter can still be moved along the vein, even with theballoon in an inflated state.

In the embodiment shown in FIG. 20, the covering 80 is coupled to anouter cannula 82 surrounding the catheter shaft and connected to anactuation mechanism or lever. The outer cannula 82 can be slid along thelongitudinal axis of the catheter to allow one end of the parachutecovering 80 to be moved axially along the catheter shaft. Duringinsertion of the catheter, the movable end of the covering is pulledaway from the connecting end of the catheter to collapse the coveringagainst the catheter. After the catheter is delivered to the venoustreatment site, the cannula 82 is slid toward the working end to deploythe covering 80 which then fills with blood entering through theopenings, thereby occluding the vein. The covering expands as it fillswith blood, and when the covering comes into contact with the vein wall,the vein is occluded. Fluid, as before, can be infused either throughperfusion holes 78 or a coaxial channel (not shown).

In the embodiment shown in the cross-sectional view of FIG. 21, thecatheter 10 includes an expandable section having a skeleton 90 disposedalong a portion of the working end of the catheter. The skeleton 90 ismore flexible than the surrounding shaft of the catheter, and can beconstructed from a metal or polymer braid. A flexible membrane 92 coversthe skeleton 90, with the ends of the membrane attached to the shaft ofthe catheter adjacent the skeleton. The membrane is preferablyconstructed from an elastomeric material. As shown in FIG. 22, when thetip of the connecting end is moved toward the working end of thecatheter, or vice versa, the skeleton 90 is deformed and forces themembrane 92 out into contact with the vein wall. This embodiment doesnot require a separate lumen to provide an inflation fluid to a balloon.The skeleton 90 is preferably resilient so that it returns to itsoriginal shape once the working end and connecting end are no longerbeing forced toward one another. Mechanisms for moving the connectingend toward the working end of the catheter for expanding the diameter ofa catheter are also discussed in U.S. patent application Ser. No.08/610,911, which has been incorporated by reference. Although theexpandable section may be controlled separately from the extension ofthe electrode, the expandable section can be controlled by the samemechanism which extends the electrodes away from the catheter.

The description of the component parts discussed above are for acatheter to be used in a vein ranging in size from 3 mm (0.12 in) to 10mm (0.39 in) in diameter. It is to be understood that these dimensionsdo not limit the scope of the invention and are merely exemplary innature. The dimensions of the component parts may be changed toconfigure a catheter 10 that may used in various-sized veins or otheranatomical structures.

When treating the veins of the lower hemorrhoidal region, the accesssite is prepared. A guide wire is passed into the vein, and advancedthrough to the venous treatment site. Alternatively, the catheter may beinserted into the vein directly and manipulated without a guide wire.The guide wire can be advanced retrograde to the venous treatment site.Several intravenous paths may be taken to the hemorrhoidal treatmentsite, and it is to be understood that other access sites can be used totreat either internal or external hemorrhoids.

A partial cross-sectional view of the venous system leading to thehemorrhoidal region is shown in FIG. 23. Hemorrhoids are generallydefined as internal or external depending on whether they are formedabove or below the dentate line DL, respectively. Internal hemorrhoidsIH are commonly formed when the smaller veins draining to the superiorhemorrhoidal vein SHV or the middle hemorrhoidal vein MHV becomedilated. External hemorrhoids are commonly formed when the smaller veinsdraining to the inferior hemorrhoidal vein IHV become dilated.

One method of delivering the catheter 122 and guide wire 120 is tointroduce the guide wire 120 into the external iliac vein EI on the sideopposite to the dilated veins of the hemorrhoid. The guide wire issteered across the bifurcated branch of the inferior vena cava IVC tothe inferior iliac vein II. The guide wire is then maneuvered intoeither the middle hemorrhoidal vein MHV to treat internal hemorrhoids,or the pudendal vein PV and then the inferior hemorrhoidal vein IHV totreat external hemorrhoids. The guide wire 120 is deployed andmaneuvered into the middle hemorrhoidal vein MHV to treat an internalhemorrhoid. The guide wire 120 is maneuvered through the venous systemuntil it reaches the dilated veins of the hemorrhoid. The catheter 122is then delivered to the venous treatment site over the guide wire 120,as shown in FIG. 23. The working end 124 of the catheter 122 includes aplurality of leads and electrodes for applying RF energy once properlypositioned at the venous treatment site to ligate or occlude the vein.The catheter should be flexible to allow tracking of the catheter overthe guide wire and through bends in the venous vascular system.Fluoroscopy, x-ray, ultrasound, or a similar imaging technique could beused to direct the specific placement of the catheter and to confirmposition within the vein.

Another method of delivering the catheter and guide wire is to introducethe guide wire into the superior hemorrhoidal vein and maneuver theguide wire through the superior hemorrhoidal vein SHV to thehemorrhoidal region. The guide wire is maneuvered into position, and thecatheter is then delivered over the guide wire to the venous treatmentsite for the internal hemorrhoid. The venous treatment site is withinthe lumen of a dilated vein, and the electrode leads expand away fromthe body of the catheter to come into apposition with the wall of thedilated vein.

When the electrode leads of the catheter 122 are positioned at thevenous treatment site, an RF generator is activated to provide suitableRF energy to cause heating of the surrounding venous tissue. The energyemitted from the electrodes is converted within the venous tissue intoheat. As previously discussed, the application of energy causes the veinto collapse and become effectively occluded or ligated.

In another anatomical region, varicose veins called esophageal varicescan form in the venous system along the submucosa of the loweresophagus, and bleeding can occur from the swollen veins. When treatingthe veins oft he lower esophageal region, the access site is prepared,and a guide wire 120 is passed into the vein and advanced through to thevenous treatment site. The guide wire can be deployed and manipulated soas to reach the treatment site for treating the esophageal varices. Thevenous treatment site is preferably within the lumen of a dilated vein.The wire is advanced to the venous treatment site, such as the level ofthe most proximal incompetent vein site which is to be treated.Preferably, the guide wire and catheter are advanced antegrade to theesophageal treatment site. Alternatively, the catheter may be insertedinto the vein directly and manipulated without a guide wire.Fluoroscopy, x-ray, ultrasound, or a similar imaging technique could beused to direct the specific placement of the catheter and to confirmposition within the vein. A properly sized catheter 122 delivers theelectrode leads to the site of venous dysfunction along the esophagealvarix. The electrodes apply RF energy or other forms of energy at asuitable power or frequency to cause the vein to collapse and becomeeffectively occluded or ligated.

As shown in FIG. 24, in a partial view oft he venous system leading tothe esophageal region, the catheter 122 is advanced over the guide wire120 to a dilated section of the vein. One method of delivering thecatheter and guide wire is to introduce the guide wire through thesuperior mesenteric vein SMV to the portal vein PV and coronary vein CVwhich branches and leads to the lower esophagus E to form the esophagealveins EV. As an alternate route, the guide wire could be introduced intothe inferior mesenteric vein, and routed through the splenic vein SV,the portal vein PV, and the coronary vein CV to arrive at the esophagealvarix to be treated.

Referring now to FIG. 25, ligation of a fallopian tube is shown. A guidewire 120 has been located in the fallopian tube F and the catheter 122is also positioned in the fallopian tube F through the fallopian tubeostium 126. The shaft of the catheter has been introduced through theuterus U with an endoscope 128. The working end of the catheter may nowbe energized as described above to perform an intra-fallopian tubeligation. The second fallopian tube may then also be ligated in the samemanner.

The lumen may be exsanguinated by compression or by a fluid flush.Further, prior to or during the application of energy to the hollowanatomical structure, the structure may be compressed or pre-sized. Theesophageal varix can be externally compressed by inflating a balloon,such as those used as a tamponade, within the esophagus to applypressure external to the esophageal varices to be treated. One methodfor compressing the lumen of the fallopian tube by external means iswith pnuemoperitoneum. In a further feature, the lumen, particularly thelumen of a fallopian tube, may be compressed by the application ofnegative pressure through the catheter. For example, in an open endcatheter, a negative pressure may be applied to the lumen at that openend. If desired, an inflatable balloon may be mounted to the shaft ofthe catheter proximal to the orifice through which the negative pressureis applied to assist in its application to the lumen. Other arrangementsare possible, such as the use of ports in the wall of the catheterthrough which negative pressure may be applied. Negative pressure canalso be applied to compress or pre-size veins.

Although described above as positively charged, negatively charged, oras a first polarity, opposite polarity, or as a positive conductor ornegative conductor, these terms are used for purposes of illustrationonly. These terms are generally meant to refer to different electrodepotentials and are not meant to indicate that any particular voltage ispositive or negative. Furthermore, other types of energy such as lightenergy from fiber optics or microwaves can be used to create a thermaleffect in the hollow anatomical structure undergoing treatment. Whilethe particular hollow anatomical structure may be a vein (e.g., varicoseveins, hemorrhoids, esophageal varices, etc.) or a fallopian tube, it isto be understood that other anatomical structures can be ligated usingthe system disclosed herein.

While several particular forms of the invention have been illustratedand described, it will be apparent that various modifications can bemade without departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

What is claimed is:
 1. A method of applying energy intraluminally to afallopian tube from a power source, the method comprising the steps of:introducing into the fallopian tube a catheter having a working end witha plurality of expandable primary leads disposed at the working end,each primary lead having a distal end and being connected to the powersource; expanding the primary leads outwardly from the working end ofthe catheter, wherein the distal ends of the primary leads move awayfrom each other and into contact with the wall of the fallopian tube;and applying energy to the fallopian tube from the distal end of theprimary leads to collapse and effectively occlude the fallopian tube. 2.The method of claim 1 further comprising the step of moving a sheath andthe plurality of expandable primary leads in relation to each other toselectively expand the primary leads outwardly or contract the primaryleads.
 3. The method of claim 1 wherein the step of introducing acatheter into the fallopian tube comprises the step of introducing aplurality of expandable primary leads that are mounted to the workingend in a cantilever arrangement.
 4. The method of claim 3 furthercomprising the step of moving a sheath away from the cantileveredexpandable primary leads such that the primary leads extend past anorifice of the sheath at the working end of the catheter and expandoutwardly.
 5. The method of claim 1 further comprising the step ofmoving the catheter in the fallopian tube during the step of applyingenergy to the fallopian tube.
 6. The method of claim 5 furthercomprising the step of compressing the fallopian tube to reduce thefallopian tube to a desired size during the step of applying energy tothe fallopian tube.
 7. The method of claim 1 wherein the step ofintroducing a catheter into the fallopian tube comprises introducing acatheter also having a secondary lead mounted at the working end, thesecondary lead having a distal end and having a length exceeding that ofthe primary leads; and wherein the step of extending the plurality ofprimary leads further includes the step of extending the secondary leadthrough the distal orifice.
 8. The method of claim 1 wherein the step ofapplying energy to the fallopian tube comprises the steps of:controlling the power source so that adjacent primary leads are ofopposite polarity while maintaining the secondary lead so that it iselectrically neutral; switching the polarity of the primary leads sothat they are all of the same polarity upon collapse of the fallopiantube around the primary leads; and controlling the power source so thatthe secondary lead is of opposite polarity relative to the primary leadsupon performing the step of switching the polarity of the primary leadsso that they are of the same polarity.
 9. The method of claim 1 whereinthe step of introducing a catheter into the fallopian tube comprisesintroducing a catheter also having an outward bend formed in eachprimary lead, the bend formed in the direction away from the otherprimary leads such that each primary lead tends to move outward awayfrom the other primary leads in the step of expanding the primary leads.10. The method of claim 1 further comprising the steps of: sensing thetemperature at a primary lead; controlling the application of power tothe primary lead in response to the temperature sensed at the lead. 11.The method of claim 1 further comprising the step of flushing thefallopian tube with fluid before the step of applying energy.
 12. Themethod of claim 1 further comprising the step of compressing thefallopian tube during the step of applying energy.
 13. The method ofclaim 12 wherein the step of compressing the fallopian tube comprisesthe step of applying negative pressure to the fallopian tube.
 14. Themethod of claim 12 wherein the step of compressing the fallopian tubecomprises the step of creating a pneumoperitoneum.
 15. The method ofclaim 1 further comprising the step of compressing the fallopian tube toa desired size before and during the step of applying energy.
 16. Amethod of applying energy intraluminally to a hemorrhoid from a powersource, the method comprising the steps of: introducing into thehemorrhoid a catheter having a working end with a plurality ofexpandable primary leads disposed at the working end, each expandableprimary lead having a distal end and being connected to the powersource; expanding the primary leads outwardly from the working end ofthe catheter, wherein the distal ends of the primary leads move awayfrom each other and into contact with the wall of the hemorrhoid; andapplying energy to the hemorrhoid from the distal end of the primaryleads to collapse the hemorrhoid to effectively occlude the hemorrhoid.17. The method of claim 16 further comprising the step of moving asheath and the plurality of expandable primary leads in relation to eachother to selectively expand the primary leads outwardly or contract theprimary leads.
 18. The method of claim 16 wherein the step ofintroducing a catheter into the hemorrhoid comprises the step ofintroducing a plurality of expandable primary leads that are mounted tothe working end in a cantilever arrangement.
 19. The method of claim 18further comprising the step of moving a sheath away from thecantilevered expandable primary leads such that the primary leads extendpast an orifice of the sheath at the working end of the catheter andexpand outwardly.
 20. The method of claim 16 further comprising the stepof moving the catheter in the hemorrhoid while continuing to applyenergy to the hemorrhoid.
 21. The method of claim 20 further comprisingthe step of compressing the hemorrhoid during the step of applyingenergy.
 22. The method of claim 16 wherein the step of introducing acatheter into the hemorrhoid comprises introducing a catheter alsohaving a secondary lead mounted at the working end, the secondary leadhaving a distal end and having a length exceeding that of the primaryleads; and wherein the step of extending the plurality of primary leadsfurther includes the step of extending the secondary lead through thedistal orifice.
 23. The method of claim 16 wherein the step of applyingenergy to the hemorrhoid comprises the steps of: controlling the powersource so that adjacent primary leads are of opposite polarity whilemaintaining the secondary lead so that it is electrically neutral;switching the polarity of the primary leads so that they are all of thesame polarity upon collapse of the hemorrhoid around the primary leads;and controlling the power source so that the secondary lead is ofopposite polarity relative to the primary leads upon performing the stepof switching the polarity of the primary leads so that they are of thesame polarity.
 24. The method of claim 16 wherein the step ofintroducing a catheter into the hemorrhoid comprises introducing acatheter also having an outward bend formed in each primary lead, thebend formed in the direction away from the other primary leads such thateach primary lead tends to move outward away from the other primaryleads in the step of expanding the primary leads.
 25. The method ofclaim 16 further comprising the steps of: sensing the temperature at aprimary lead; controlling the application of power to the primary leadin response to the temperature sensed at the lead.
 26. The method ofclaim 16 further comprising the step of flushing the hemorrhoid withfluid before the step of applying energy.
 27. The method of claim 16further comprising the step of compressing the hemorrhoid to a desiredsize before and during the step of applying energy.
 28. The method ofclaim 27 wherein the step of compressing the hemorrhoid comprises thestep of applying negative pressure to the hemorrhoid.
 29. The method ofclaim 16 further comprising the step of exsanguinating the hemorrhoidbefore and during the step of applying energy.
 30. The method of claim29 wherein the step of exsanguinating the hollow anatomical structurecomprises the step of delivering fluid to displace blood from thehemorrhoid.
 31. A method of applying energy intraluminally to anesophageal varix, the method comprising the steps of: introducing intothe esophageal varix a catheter having a working end with a plurality ofprimary leads disposed at the working end, each primary lead having adistal end; expanding the primary leads outwardly from the working endof the catheter, wherein the distal ends of the primary leads move intocontact with the wall of the esophageal varix; and applying energy tothe esophageal varix from the distal end of the primary leads tocollapse the esophageal varix to effectively occlude the esophagealvarix.
 32. The method of claim 31 further comprising the step of movinga sheath and the plurality of expandable primary leads in relation toeach other to selectively expand the primary leads outwardly or contractthe primary leads.
 33. The method of claim 31 wherein the step ofintroducing a catheter into the esophageal varix comprises the step ofintroducing a plurality of expandable primary leads that are mounted tothe working end in a cantilever arrangement.
 34. The method of claim 33further comprising the step of moving a sheath away from thecantilevered expandable primary leads such that the primary leads extendpast an orifice of the sheath at the working end of the catheter andexpand outwardly.
 35. The method of claim 31 further comprising the stepof moving the catheter in the esophageal varix while continuing to applyenergy to the esophageal varix.
 36. The method of claim 31 furthercomprising the step of compressing the esophageal varix during the stepof applying energy.
 37. The method of claim 31 wherein the catheterfurther includes a secondary lead mounted at the working end, thesecondary lead having a distal end and having a length exceeding that ofthe primary leads.
 38. The method of claim 37 wherein the step ofapplying energy to the esophageal varix comprises the steps of:controlling the power source so that adjacent primary leads are ofopposite polarity while maintaining the secondary lead so that it iselectrically neutral; switching the polarity of the primary leads sothat they are all of the same polarity upon collapse of the esophagealvarix around the primary leads; and controlling the power source so thatthe secondary lead is of opposite polarity relative to the primary leadsupon performing the step of switching the polarity of the primary leadsso that they are of the same polarity.
 39. The method of claim 31wherein the step of introducing a catheter into the esophageal varixcomprises introducing a catheter also having an outward bend formed ineach primary lead, the bend formed in the direction away from the otherprimary leads such that each primary lead tends to move outward awayfrom the other primary leads in the step of expanding the primary leads.40. The method of claim 31 further comprising the steps of: sensing thetemperature at a primary lead; controlling the application of power tothe primary lead in response to the temperature sensed at the lead. 41.The method of claim 31 further comprising the step of flushing theesophageal varix with fluid before the step of applying energy.
 42. Themethod of claim 31 further comprising the step of compressing theesophageal varix to a desired size before the step of applying energy.43. The method of claim 42 wherein the step of compressing theesophageal varix comprises the step of applying negative pressure to theesophageal varix.
 44. The method of claim 42 wherein the step ofcompressing the esophageal varix comprises the step of applying pressureexternal to the esophageal varix from within the esophagus.
 45. Themethod of claim 31 further comprising the step of exsanguinating theesophageal varix before and during the step of applying energy.
 46. Themethod of claim 45 wherein the step of exsanguinating comprises the stepof delivering fluid to displace blood from the esophageal varix.
 47. Amethod of applying energy intraluminally to a hollow anatomicalstructure, the method comprising the steps of: introducing into thehollow anatomical structure a catheter having a working end with aplurality of primary leads disposed at the working end, each primarylead having a distal end; expanding the primary leads outwardly from theworking end of the catheter, wherein the distal ends of the primaryleads move into contact with the hollow anatomical structure; andapplying energy to the hollow anatomical structure from the distal endsof the primary leads to reduce the inner diameter of the hollowanatomical structure to effectively occlude the hollow anatomicalstructure.
 48. The method of claim 47 further comprising the step ofmoving a sheath and the plurality of expandable primary leads inrelation to each other.
 49. The method of claim 47 wherein the pluralityof expandable primary leads are mounted in a cantilever arrangement. 50.The method of claim 47 further comprising the step of moving thecatheter in the hollow anatomical structure during the step of applyingenergy to the hollow anatomical structure.
 51. The method of claim 47further comprising the step of compressing the hollow anatomicalstructure during the step of applying energy.
 52. The method of claim 47wherein the catheter further includes a secondary lead mounted at theworking end, the secondary lead having a distal end and having a lengthexceeding that of the primary leads; and further comprising the step ofapplying energy to the hollow anatomical structure from the distal endof the secondary lead separately from the step of the applying energyfrom the distal ends of the primary leads.
 53. The method of claim 47wherein the step of introducing a catheter into the hollow anatomicalstructure comprises introducing a catheter also having an outward bendformed in each primary lead, the bend formed in a direction away fromthe other primary leads such that each primary lead tends to moveoutward away from the other primary leads in the step of expanding theprimary leads.
 54. The method of claim 47 wherein the energy iselectrical energy.
 55. The method of claim 47 wherein the energy islight energy.
 56. The method of claim 47 further comprising the step offlushing the hollow anatomical structure with fluid before the step ofapplying energy.
 57. The method of claim 47 further comprising the stepof compressing the hollow anatomical structure to a desired size beforethe step of applying energy.
 58. The method of claim 57 wherein the stepof compressing the hollow anatomical structure includes the step ofapplying negative pressure to the hollow anatomical structure.
 59. Themethod of claim 57 wherein the step of compressing the hollow anatomicalstructure includes the step of applying pressure external to the hollowanatomical structure.
 60. The method of claim 47 further comprising thestep of exsanguinating the hollow anatomical structure before and duringthe step of applying energy.
 61. The method of claim 60 wherein the stepof exsanguinating the hollow anatomical structure includes the step ofdelivering fluid to displace previously present fluid from the hollowanatomical structure.
 62. The method of claim 47 further comprising thestep of ceasing the step of applying energy to the hollow anatomicalstructure such that the hollow anatomical structure is effectivelyoccluded without significant formation of coagulum.
 63. The method ofclaim 47 wherein a portion of the distal ends of the primary leads isinsulated so as to prevent formation of coagulum in the hollowanatomical structure during the step of applying energy.
 64. The methodof claim 47 wherein the distal ends of the primary leads move towardeach other when the inner diameter of the hollow anatomical structure isreduced.
 65. The method of claim 31 wherein a portion of the distal endsof the primary leads is insulated so as to prevent coagulation of bloodin the varix during the step of applying energy.
 66. The method of claim31 wherein a portion of the distal ends of the primary leads isinsulated so as to prevent heating of the blood in the varix during thestep of applying energy.